DC Motor drive assembly having a controller/charge with regenerative braking

Abstract

A drive assembly comprises a DC electric motor and an integrated charger/controller/regenerator which includes a power module, a step-down module and a control circuit. The input of the power module is connected to an electric power source during charging, and to the DC motor during regenerative braking. The input of the step-down module is connected to the power module, and the output is connected to the battery. The control circuit includes a multiplicity of switches, and has three modes of operation: driving, regenerative braking and charging. During driving, the switches connect the battery to the power module input and the power module output to the DC motor. During regenerative braking, the switches connect the DC motor to the power module input and the power module output to the step-down module input, and the step-down module output charges the battery. During charging, the switches connect the power module output to the step-down module input, and the step-down module output charges the battery.

Having thus described the invention, what is claimed is: 
     
       1. A drive assembly comprising: (i) a DC electric motor; and (ii) an integrated charger/controller/regenerator for controlling said DC electric motor in a drive mode of operation, for charging a battery in a regenerative braking mode of operation, and for connection to an electric power source for charging the battery in a charge mode of operation including (a) a power module having an output and an input for connection to the associated electric power source during a charge mode of operation, said input of said power module being connected to said DC motor during a regenerative braking mode of operation in which said power module provides a DC current to said output;   (b) a step-down module having an input connected to said power module and an output adapted to be connected to terminals of an associated battery;   (c) a control circuit including switch means having a multiplicity of switches, said control circuit having (i) selected ones of said switches selectively effect the connection of the terminals of the associated battery to said input of said power module and selected ones of said switches selectively effect the connection of said output of said power module to said DC motor wherein said power module controls said DC motor;   (ii) a regenerative braking mode of operation during which selected ones of said switches selectively effect the connection of said DC motor to said input of said power module and selectively effect the connection of said output of said power module to said input of said step-down module, said output of said step-down module being connectable to the terminals of the associated battery to effect charging thereof; and   (iii) a charge mode of operation during which said input of said power module is connected to the associated electric power source, selected ones of said switches selectively effect the connection of said output of said power module to said input of said step-down module, said output of said step-down module being connectable to the terminals of the associated battery to effect charging thereof.     
     
     
       2. The drive assembly according to claim 1 wherein said step-down module includes a transistor, a diode and an inductor, said transistor being connected in parallel with said diode and connected in series with said inductor. 
     
     
       3. The drive assembly according to claim 2 wherein another transistor is connected in parallel with said diode and said inductor of said step-down module, said other transistor controlling the DC current output of said DC motor during said regenerative braking mode of operation. 
     
     
       4. The drive assembly according to claim 3 wherein said power module includes said transistor of said step-down module, and wherein said transistor is closed and said other transistor is pulse width modulated to periodically short circuit said DC motor to reverse the direction of the current to charge the battery during said regenerative braking mode of operation. 
     
     
       5. The drive assembly according to claim 4 wherein said power module is a programmable pulse width modulated converter having power transistors and a parallel/series switching system which connects said power transistors in series during said charge mode of operation, wherein said power transistors rectify the associated AC current input to said DC current output of said power module and said parallel/series switching system connects said power transistors in parallel during said drive mode of operation to control the associated DC motor. 
     
     
       6. The drive assembly according to claim 1 wherein the voltage of said output of said step-down module is not greater than 100 volts.